Emission Computed Tomography (ECT) has been widely used in medicine for diagnosis and other purposes. A subject, such as a patient, may be scanned by a scanner to obtain medical images. When the medical imaging system is used for chest or upper abdomen examinations, respiratory motion of the lungs and/or cardiac movements of the heart of a subject may lead to motion blur in the medical images. The motion blur may be reduced by using a gating approach.
A single field of view of a total-body PET scanner may cover the entire body of a subject. Various regions of the entire body of the subject may move to various degrees during the scanning of the subject. A conventional gating approach may be inapplicable to the total-body PET scanner as it would divide the data of entire body into different frames covering different motion phases, while noticeable motions may occur only in selected regions of the body such as the chest and the abdomen. It is desirable to develop methods and systems for reconstructing data acquired by a total-body PET scanner with reduced motion blur without over-gating of a region of the subject that is not significantly affected by the motion of the subject during the scanning.